It is essential to avoid smoking and keep weight, blood sugar levels and blood pressure under control as these risk factors in middle age may cause the brain to shrink, leading to mental declines up to a decade later.

Evaluating data from 1,352 participants whose average age was 54 years in the Framingham Offspring Study which began in 1991 – researchers found that smoking, high blood pressure, diabetes and being overweight were each linked to potentially dangerous vascular changes in the brain, Health News reported.

Participants were given blood pressure, cholesterol and diabetes tests and had their body mass and waist circumference measured.

They also underwent MRI brain scans over the course of a decade, the first one about seven years after the initial risk factor exam.

Those with stroke and dementia were excluded at the outset, and between the first and last MRIs 19 participants suffered a stroke and two developed dementia.

Those with high blood pressure experienced a more rapid worsening of test scores of planning and decision-making, which corresponded to a faster rate of growth of small areas of vascular brain damage than those with normal blood pressure.

Those with diabetes in middle age experienced brain shrinkage in an area known as the hippocampus faster than those without, and smokers lost brain volume overall and in the hippocampus faster than non-smokers, with a more rapid increase of small areas of vascular brain damage.

Meanwhile, participants who were obese at middle age were more likely to be in the top 25 per cent of those with faster declines in tests of executive function.

Those with a high waist-to-hip ratio were more likely to be among the 25 per cent with a faster drop in brain volume.

The findings provide evidence that identifying these risk factors early in people of middle age could be useful in screening people for at-risk dementia and encouraging people to make changes to their lifestyle before it’s too late.

“We can’t cure aging, but the idea of a healthy body, healthy mind is very real. People should stop smoking, control their blood pressure, avoid diabetes and lose weight.